The present invention is directed to a crankcase emission control system. The crankcase emission control system is useful for heavy internal combustion engines, such as diesel engines.
Emission control systems for internal combustion engines have become increasingly important as concerns over environmental damage and pollution have risen prompting legislators to pass more stringent emission controls. Much progress has been made in improving exhaust emission control systems. However, crankcase emission control systems have been largely neglected.
Crankcase emissions result from gas escaping past piston rings of an internal combustion engine and entering the crankcase due to high pressure in the cylinders during compression and combustion. As the blow-by gasses pass through the crankcase and out the breather, the gasses become contaminated with oil mist, wear particles and air/fuel emissions. Some diesel engines discharge these crankcase emissions to the atmosphere through a draft tube or similar breather vent, which contributes to air pollution. The crankcase emissions can also be drawn into the engine intake system causing internal engine contamination and loss of efficiency.
Relatively few heavy diesel engines have crankcase emission controls. Crankcase emission control systems filter the crankcase particulate emissions and separate the oil mist from the crankcase fumes. The separated oil is collected for periodic disposal or return to the crankcase. The crankcase emission control systems increase engine performance and decrease maintenance intervals and site/critical engine component contamination. The systems are also becoming increasingly important in reducing air pollution.
Crankcase emission control systems may be xe2x80x9copenxe2x80x9d or xe2x80x9cclosedxe2x80x9d systems. In open systems, the cleaned gases are vented to the atmosphere. Although open systems have been acceptable in many markets, they pollute the air by venting emission to the atmosphere and can suffer from low efficiency. In a closed system, the crankcase breather is connected to the inlet of the closed crankcase emission control system. The outlet of the system is connected to the engine air inlet, where the filtered blow-by gas is recycled through the combustion process. Closed systems eliminate crankcase emissions to the atmosphere, meet strict environmental regulations, and eliminate site and external critical component contamination.
One of the first closed systems, developed by Diesel Research, Inc. of Hampton Bays, N.Y., includes a two-component crankcase pressure regulator and a filter. The filter removes particles to prevent contamination of turbochargers, aftercooler, and internal engine components. The pressure regulator maintains acceptable levels of crankcase pressure over a wide range of crankcase gas flow and inlet restrictions. Because the pressure regulator is a separate component from the filter, additional plumbing and space is required for the system. This creates significant installation and maintenance costs for the system.
A recent improvement to closed crankcase emission control systems is shown in U.S. Pat. No. 5,564,401, also owned by Diesel Research, Inc. In this system, a pressure control assembly and a filter are integrated into a single compact unit. The pressure control assembly is located in a housing body and is configured to regulate pressure through the system as well as agglomerate particles suspended in the blow-by gasses. Inlet and outlet ports direct the blow-by gasses into and out of the housing body from the engine block. A filter housing enclosing a replaceable filter element is removably attached to the housing body to separate any remaining oil from the blow-by gasses. The filter element can be easily removed from the filter housing for replacement, after removing the filter housing from the housing body. The separated oil drains down and collects in a reservoir at the bottom of the filter housing. An oil drain is located in the bottom wall of the filter housing, and includes a free-floating (one-way) check valve. The check valve is connected through a separate return line to the oil pan or engine block to return the collected oil to the engine. The system is compact and combines various components into a single integrated unit, is efficient, and is simple and inexpensive to manufacture.
While there are many advantages to the emission control system shown in the Diesel Research patent, the oil collecting on the inside surface of the media ring drains down onto the lower end cap, and then must make its way radially outward through the media, before it then drips down into the oil reservoir area for return to the engine. The return path through the media can be obstructed as the filter element becomes spent, which results in the oil being retained in the element and thereby less oil being returned to the engine crankcase. Spillage of the oil can occur during an element change, which can create handling issues.
The check valve in the housing for the Diesel Research system can also become clogged and/or worn over time, and have to be removed and replaced. Since the check valve is part of the filter housing, this generally means replacement of the entire (relatively expensive) filter housing, and also keeping a separate maintenance schedule for the filter housing/check valve.
Still further, the return line for the oil is a separate component from the crankcase emission line from the engine. This requires separate plumbing between the engine and emission control system, and generally increases the material, installation and maintenance costs associated with the system.
A further improved filter assembly for a crankcase emission control system is shown in U.S. Pat. No. 6,161,529, owned by the assignee of the present invention and which is incorporated herein by reference. In this assembly, oil collected in the filter drains directly into a sump chamber (not through the filter media), and can be returned through a check valve to the engine. The oil drains back through the crankcase emissions line, which reduces the number of lines needed to and from the engine. The check valve is also integral with the filter element, and is thereby replaced at the same time the filter element is replaced. Thus, this assembly addresses some of the drawbacks of the Diesel Research System.
Nevertheless, in certain application, it has been found that a volume of engine oil can be drawn into the air intake of the diesel engine, such as if the vehicle is located on an extreme angle, or if a roll-over occurs. In these situations, oil can accumulate above the cylinder head, and if it flows into the crankcase emission control system, the engine can run uncontrollably on the ingested oil.
Thus, it is therefore believed there is a demand in the industry for a still further improvement, most notably an improved crankcase emission control system which prevents oil from passing through the system and being ingested by the engine; and still provides a system that is compact and combines various components into a single integrated unit, is efficient, and is simple and inexpensive to manufacture.
The present invention provides a novel and unique crankcase emissions control system. Oil collecting in the cylinder head is prevented from passing through the emission control system by a shut-off valve. The shut-off valve floats on the oil surface, and rises with the oil to close the air intake. The shut off valve is of simple construction, and can be combined with the filter assembly, in a center tube integral with the housing, or in inlet or outlet fittings for the crankcase emissions control system. A pressure relief valve can also be provided upstream from the shut-off valve to relieve excess system pressure.
According to a first embodiment of the present invention, the shut off valve comprises a cylindrical float member with a supporting body and a seal. The body includes a guide member to maintain the float member in a proper orientation with respect to the gas passage leading to the engine. The float member floats with the level of oil in the housing of the emission control system, and when the oil level increases to the level of the gas passage, the seal on the float member fluidly seals against a valve seat at the opening to the passage to prevent oil passing to the engine. When the oil level drops, the float member drops as well, and allows the gas to again pass to the engine.
The shut off valve can be incorporated in the filter element, and in such case it is preferred that one end cap of the element include a well area to support an guide the float member; or alternatively, the shut off valve can be incorporated into a central support tube integral with the housing of the emissions control system. The central support tube would likewise have appropriate structure to guide the float member. According to further embodiments, the float member can be a hollow ball and be guided within a passage into position against a valve seat. The shut-off valve in these embodiments can be incorporated into the cover of the crankcase, or into inlet or outlet fittings to the housing.
The pressure relief valve can be provided upstream from the shut-off valve to relieve excess pressure in the system when the shut-off valve is in a closed position. The pressure relief valve and shut-off valve can be mounted together in the inlet fitting or in the outlet fitting, or the pressure relief valve can be located in the inlet fitting, while the shut-off valve is located in the outlet fitting.
The crankcase emission control assembly of the present invention thereby prevents oil passing through the crankcase emission control system and being ingested by the engine; and still provides a system that is compact and combines various components into a single integrated unit, is efficient, and is simple and inexpensive to manufacture.
Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.